Field of the Invention
The invention relates to a vessel suited to lifting and lowering floating vessels and other loads while relying mainly if not entirely on static buoyancy, to transporting loads over bodies of water, and to an application of that vessel to marine salvage and cleanup operations including removal of oil from an oil spill.
“TOMCAT” as used herein refers to a utility catamaran as described, having a rigid deck, static buoyancy, and mechanical actuator means to raise or lower the deck with respect to the water line. For example a mid-range seagoing size has two 30 m hulls and a displacement of 30 tonnes. The dimensions of the TOMCAT may be scaled up or down, to suit any application.
Description of the Related Art
90% of internationally traded goods are carried on merchant ships that require periodic hull maintenance and anti-fouling treatment, and must be raised out of the water for such work to be done. In the same way, recreational vessels too large to be taken from the water on an automobile trailer require lifting and hull maintenance.
Marine salvage and clean-up further requires reliable means for carrying and lifting loads, often far from land. This presents the challenge of lifting loads from a floating platform whose stability is not assured. Existing means for marine lifting such as floating dry-docks typically use variable buoyancy. But variable buoyancy lifts inherently have poor stability, especially if the buoyant effect is affected by submersion pressure.
Many maritime events; deliberate or accidental, result in petroleum-related compounds polluting a body of water. Very large incidents are not uncommon. Spilled oil, lost containers, and other environmental threats demand an effective clean-up response. For example the 2010 Deepwater Horizon spill in the Gulf of Mexico, and the 2011 Rena spill of oil and shipping containers off the coast of Tauranga in New Zealand. With increased interest in offshore drilling, there is a continuing risk of further spills. Much harm including to wild life and to the fishing industry is caused when spilled oil reaches coastlines. The current state of the art in oil recovery relies on very large vessels which are kept in remote countries, or use of relatively small skimmers.